Applies To:
  • CitectSCADA
  • CitectHMI

While trying to install Citect on a Win2000 operating system, I am ~90% complete with the installation process when I receive the following error:

16-bit MS-DOS Subsystem

<Drive>:\<Program Path>

XXXX. An installable Virtual Device Driver failed DLL initialization. Choose 'Close' to terminate the application.


16-bit MS-DOS Subsystem

<Drive>:\<Program Path>

SYSTEM\CurrentControlSet\Control\VirtualDeviceDrivers. VDD. Virtual Device Driver format in the registry is invalid.

Choose 'Close' to terminate the application.

In some cases, clicking the 'Ignore' button allows the program to run properly, but the error message continues to be displayed when you start the program.

This behavior can occur if the following registry value has become corrupted:


This is a bug that has been known to occur in the following Win2000 operating systems: Win2000 Server, Win2000 Advanced Server and Win2000 Professional. Installing Service Pack 2 or 3 may help to repair this corruption. If it does not, then the Virtual Device Driver (VDD) subkey must be repaired by using the Windows Registry Editor in the following way:

WARNING: If you use the Windows Registry Editor incorrectly, you may cause serious problems that may require you to re-install your operating system. Use Registry Editor at your own risk.

1. Start Registry Editor by running Regedt32.exe in Start menu | Run...

2. Locate and click the following value:


3. In the Edit menu, click 'Delete'.

4. In the Edit menu, click 'Add Value'.

5. Type VDD in the 'Value Name' box, click 'REG_MULTI_SZ' for the Data Type, and then click 'OK'.

6. The Multi-String editor appears. Leave this entry blank and click 'OK'.

7. Exit the Registry Editor.

If the above steps do not work, or if you are unable to create the VDD subkey, it may be necessary to also delete and re-create the whole 'VirtualDeviceDrivers' registry key.